Math 115
N. Psomas
Chapter 4 (Sections 4.3 - 4.4) Homework Solutions
Section 4.3
4.53 Discrete or continuous. In each of the following situations decide if the random variable is
discrete or continuous and give a reason for your answer.
(a) Your Web page
Math 115 Probability & Statistics
Section 1.2 HW
Section 1.2 Exercises (Solutions)
HW: 1.66, 1.67*, 1.73*, 1.74*, 1.75*, 1.77*, 1.78*, 1.86*
1.66 Salaries of the New York Mets. The mean salary of the players on the 2008 New York Mets
baseball team was $4,
Chapter 7 Solutions
7.1. (a) The standard error of the mean is
df = n 1 = 15.
s
n
=
$96
16
= $24. (b) The degrees of freedom are
7.2. In each case, use df = n 1; if that number is not in Table D, drop to the lower degrees
of freedom. (a) For 95% condence
Chapter 8 Solutions
8.1. (a) n = 760 banks. (b) X = 283 banks expected to acquire another bank.
.
(c) p = 283 = 0.3724.
760
8.2. (a) n = 1063 adults played video games. (b) X = 223 of those adults play daily or almost
223 .
daily. (c) p = 1063 = 0.2098.
.
Chapter 6 Solutions
6.1. x = / 25 =
$2.50
5
= $0.50.
6.2. Take two standard deviations: 2
$2.50
5
= 2 $0.50 = $1.00.
6.3. As in the previous solution, take two standard deviations: $1.00.
Note: This is the whole idea behind a condence interval: Probabili
Chapter 3 Solutions
3.1. Any group of friends is unlikely to include a representative cross section of all students.
3.2. Political speeches provide a good source of examples.
3.3. A hard-core runner (and her friends) are not representative of all young p
MATH 115
Chapter 4 Homework Solutions
Section 4.5
N. PSOMAS
4.103 Exercise and sleep. Suppose 40% of adults get enough sleep, 46% get enough exercise,
and 24% do both. Find the probabilities of the following events:
(a) enough sleep and not enough exercis
MATH 115
CHAPTER 4 HOMEWORK
Sections 4.1 - 4.2
N. PSOMAS
4.6 Winning at craps. The game of craps starts with a come-out roll where the shooter rolls a
pair of dice. If the total is 7 or 11, the shooter wins immediately (there are ways that the shooter
can
CAS MA 115 Statistics I Fall 2010 Lecture 7.1-7.3
Lecture 7.1
Statistics may be defined as "a body of methods for making wise decisions in the face of
uncertainty." ~W.A. Wallis
1)
2)
3)
Sampling Distribution for Population Proportion
Confidence Intervals